Medical tubes are used to directly feed a nutritional supplement or a medicine into a living body (into stomach and intestine), diagnose or sometimes treat a problematic site inside the living body (inside of the intestine) without opening abdomen.
For example, in the case of an obstruction of a small intestine (small-intestinal obstruction), if the distal end (tip end) of the medical tube can be guided to a proper position, this contributes to improvement of symptoms caused by the expansion of the intestine, and a definite diagnosis (identification of obstruction site and the cause), by reducing the internal pressure of a region of the inside of the small intestine which is more oral side than an obstruction site having been expanded due to the obstruction. By reducing the internal pressure of the intestine (intestinal tract) in this way, the obstruction is eliminated and a treatment is realized in many cases, as well as the improvement of the symptoms and the diagnosis. The medical tube used for the purpose of such a pressure-reduction treatment of the intestine is commonly inserted through a nose, and its distal end is required to be moved to a proper position in the inside of the intestine, beyond stomach and duodenum (the tube stays in the inside of the intestine for a couple of days, and therefore, the tube cannot be virtually inserted through the mouth).
In contrast, depending on the kind of the nutritional supplement or the kind of a disease, the nutritional supplement or the medicine is often required to be fed to a region of the small intestine which is more distant from the mouth than the duodenum is. In this case, typically, the nutritional supplement or the medicine continues to be fed to the region for a specified time in a particular way by use of an infusion machine. If the tube does not sufficiently reach the region of the small intestine, the nutritional supplement flows back to the inside of the stomach, which causes a risk of vomiting and aspiration. In view of this situation, the position of the distal end of the tube is important (in this case, also, the tube is inserted through the nose).
Typically, the tube can be easily inserted into the stomach in a general hospital room. However, it is not easy to insert the medical tube into the small intestine. The medical tube is moved through a narrow site at the exit of the stomach, namely, pylorus, through C-loop of the duodenum which is bent, and through a flexural area of duodenojejunal flexure, and eventually reaches the small intestine. For this reason, typically, when the tube is inserted, a patient is carried to a X-ray TV room, and the tube is inserted while seeing radioscopy by use of a contrast medium (barium obstructs (occludes) the tube and therefore cannot be used as the contrast medium in the present embodiment, and a contrast medium called Gastrografin for digestive tract, which is similar to barium and is viscosity-eliminated, is used). However, in some cases, due to the body construction or deformation of the stomach of the patient, etc., the tube cannot reach even the duodenum even under fluoroscopic guidance. The tube is pushed at the nose in the outside of the patient's body and moved into the body. The tube which is long is not tough (stiff) and a force is not well transferred to the distal end of the tube. Under this state, the tube cannot be moved smoothly. As a solution to this, it is often considered that the medical tube can be easily moved by use of an upper endoscopic instrument. For example, Japanese Laid-Open Patent Application Publication No. Hei. 8-38612 (hereinafter will be referred to as “Patent Literature 1”) discloses that a ring is attached to the distal end of a medical tube and grasped by forceps, and the distal end of the tube is pulled and moved to the former half part (part closer to the mouth) of the duodenum while pulling the distal end of the tube. In this state, the ring may be released from the forceps, and the endoscopic instrument may be pulled out in a state in which the distal end of the tube is free. However, it is difficult to actually perform this. Even when the endoscopic instrument is pulled out gently, the tube and the endoscopic instrument contact each other in an adhesive state in the flexural area of the duodenum or the narrow pylorus. By pulling out the endoscopic instrument, the distal end of the tube is often moved back to the inside of the stomach together with the endoscopic instrument.
The distal end of the medical tube disclosed in Patent Literature 1 is moved through the flexural site such as the stomach and the narrow site such as the pylorus valve and reaches the obstruction site. The medical tube can be delivered (carried) by the endoscopic instrument and moved through the flexural site and the narrow site. However, at the flexural site and the narrow site, the medical tube and the endoscopic instrument contact each other in an adhesive state. Therefore, the medical tube is pulled back together with the endoscopic instrument, by pulling out the endoscopic instrument, before a treatment is performed for the obstruction site. For this reason, the distal end of the medical tube is sometimes deviated from the obstruction site after it has been delivered to the obstruction site. Thus, the distal end of the medical tube is sometimes deviated from a desired site after it has been delivered to the obstruction site, by pulling out the endoscopic instrument.
In view of the above, an object of the present invention is to provide a medical tube which is capable of surely delivering its distal end to a desired site.